Manufacture of hydrocarbon products



internatik 0a. 19, 1943 uNlTED sfrA'rs's PATENT oFFlcs MANUFACTURE oFHYDBOCARBON PRODUCTS ,Louis A. Clarke and George B. Hatch, Fishkill, andErnest F. Pevere, Beacon, N. Y., assignors to The Texas Company, NewYorlr, N. Y., a

A.corporation ofv Delaware Application October 22, 1942, Serial No.462,898

s claims. (ci. 26o-6831i e tion of sulfuric acid under suitablepolymerizingy y conditions so as to effect substantial conversion ofcli-isobutylene to tri-isobutylene Without substantial production ofpolymers of higher molecular weight than tri-isobutylene.

It has been known heretofore to treat isobutylene with ysulfuric acidunder polymerizing conditions so as to' effect polymerization.y Theresult- 'ing polymer product obtained contains both diisobutylene andtri-isobutylene as well as higher molecular Weight polymers. Accordingto the information available heretofore it would be exsulfuric acidunder polymerizing conditions tetraisobutylene would be obtained.

However and in accordance with this invention, it has been found thatcontrary to normal expectations the dimer, di-isobutylene, can besubjected to the action of sulfuric acid so as to effect conversion ofthe dimer to the trmer without substantial production of the tetramer.

More speciflcally the invention involves treatying di-isobutylene or ahydrocarbon feed consisting essentially of di-isobutylene with sulfuricacid'of about 60 to 85% HaSO4 and preferably about 70% H2804. Thetreatment is effected at a temperature in the range about 100 to 250 F.and preferably within the range about 150 to 200 F., employing a time ofcontact between hydrocarbons and acid ranging from about l to 2 6minutes. The acid may be employed in the pro- Y portion of about 0.3 to3.0 volumes of acid per volume of dimer in the reaction zone, theprepeoted that when di-isobutylene is subjected to l Within the rangeabout 285 toiOOo F. so that the fuel product will have an open-cup flashof not more than about 105 F. Tri-isobutylene, since it has'a boilingpoint of about 354 F., therefore, s

provides a desirable hydrocarbon component for safety fuel Whereas thedimer and tetramer compounds cannot be used in substantial amounts sincethey have boiling points outside this preferred range for safety fuel.

According to a modification of the invention iso-butylene or a C4hydrocarbon fraction containing isobutylene may be treated with sulfuricacid under polymerizing conditions so as to ob,l

tain a product comprising the dimer and trimer as well as some othermaterial including higher molecular Weight polymers and unreactedhydrocarbons. This product may be fractionated to separate therefrom afraction consisting essentially of thedimer and this dimer fraction thensubjected to further treatment with sulfuric acid in a separate treatingzone in accordance with the procedure set forth above for conversion tothe trimer. This preliminary treatment Yof the C4 fraction with sulfuricacid may involve the so-called 'cold sulfuric acid process forpolymerization or the so-called hot acid polymerization process as willbe described in more detail later.

In order to describe the invention further reference will now be made tothe accompanying drawing. l

As indicated in the drawing a hydrocarbon feed consisting essentially ofCi hydrocarbons including isobutylene is conducted from a source notshownthrough a pipe I to an absorber Z wherein the feed hydrocarbons aresubjected to countercurrent contact with sulfuric acid introducedthrough a pipe 3. The Aconditions of operation maintained in theabsorber 2 correspond substantially to those employed in theconventional cold sulfuric acid process. Thus the acid introducedthrough the pipe 3 contains about 60 to H2804 and the temperaturemaintained within the absorber 2 is in the range about 60 to 100 F. I f

The acid and hydrocarbons are introduced in the ratio of about 1 part ofacid per part of hydrocarbon by volume.

Under these conditions about of the isobutylene contained in the feedhydrocarbon mixture is absorbed in the acid. The unabsorbed hydrocarbonswhich may comprise normal parafns as well as some normal butylenes aredischarged through a pipe 4.

The solution of isobutylene in sulfuric acid is mixture separates intophases. i continuously withdrawn and recycled all or -in a pipe 5 andpassed through a heater 5 wherein polymerization is effected. Thetemperature in v the heater 6 is in the range about 140 to 200 F. andthe reaction time is usually about 1 minute so that the polymer productmay comprise about 75% dimer and 25% trimer. This product iscontinuously drawn ofiV to a separator l wherein the The acid phase ispart through a pipe 8 to the previously mentioned pipe 3. Thehydrocarbon phase is continuously drawn off through a pipe 9 to afractionating still l wherein the hydrocarbons are subjected tofractionation .to segregate a fraction rich in the dimer. It '.wi11 beunderstood. of course, that prior to fractionation the hydrocarbons maybe subjected to treatment with a neutralizing agent such as caustic sodaor other suitable alkaline material for the purpose of removingremaining acid.

In the fractionation, a light fraction comprising isobutylene (monomer)may be removed through a pipe Ii and. this material may be recycled allor in part to the absorber'2.

An intermediate fraction consisting essentially of the dimer is removedthrough a pipe i2 while the higher boilingfraction comprising the trimeris removed through a pipe I8.

The dimer fraction is conducted through the pipe l2 to a polymerizer I4wherein the fraction is subjected to further treatment with sulfuricacid to effect conversion to the trimer. The acid employed at this stagemay contain from 60 to 85% I-IzSO-i and preferably about 70% HrSOi. Theacid may be fresh, regenerated or used acid.

The reaction is effected at a temperature in the range about 100 to 250F. and preferably in the range between 150 to 200 F. employing a contacttime between acid and hydrocarbon undergoing treatment of to 20 minutes.The ratio of acid to dimer undergoing treatment is maintained within therange about 0.3 to 3.0 volumes of acid per volume of dimer.

The resulting polymer product is .conducted through a pipe I5 to aseparator i5 wherein phase separation occurs. The acid phase is drawnoff from a pipe il and may be recycled all or in part to thepolymerizing unit I4.

The hydrocarbon phase is drawn off through a pipe i8 to a fractionatingstill I9, wherein the hydrocarbons are fractionated so as to separatelyrecover the trimer and unreacted dimer. The unreacted dimer isadvantageously returned through a pipe to the polymerizer i4 for furthertreatment. The small amount of lower 'molecular weight material may beremoved as a separate fraction throughs. lpipe 2l while any higherboiling residue isseparated as another fraction and removed through apipe 22, the trimer or trimer fraction being discharged through a pipe23.

As already indicated the primary stage may involve the so-called hotacid polymerization process in which type of operation absorption andpolymerization of isobutylene is eected in a single step. In this typeof operation acid of about 63 to 70% H2504 is employed at a temperaturein the range about 160 to 220 F. with a time of contact about 10 to 15minutes.

By way of specic example a feed consisting of di-isobutylene is treated.in a continuous reactor with ,80% HzSOi acid, the reaction productsbeing discharged to an acid settler wherein acid is separated from thehydrocarbon. The hydrocarbon is fed continuously to the reactor in whichan acid to hydrocarbon volume ratio of 1.5:1 is maintained by acidrecycle from the settler. The contact time for the hydrocarbons isfifteen minutes at a temperature of 120 F.

Thereafter the treated hydrocarbons are separated from the catalyst andfractionally distilled into three liquid fractions, namely, a dimerfrac- 4tion boiling up to about 329 F., a trimer fraction boiling intherange 329 to 365 F. and a residual fraction boiling above 365 F. Thevolume per cent of each fraction obtained is as follows:

Per cent Dmer fraction` 31.1 Trimerfraction-- 62.2 Residual fraction 6.7

Thus, it is seen that the feed hydrocarbon 1s converted into a productof which 62.2% by volume consists mainly of the trimer, the amount olhigher molecular weight polymer material being Y pound. In,the case ofthe two stage operation either substantially pure isobutylene or anormally gaseous hydrocarbon mixture comprising isobutylene may be usedas the initial feed.

Obviously many modifications and variations of the invention, ashereinbefore set forth may be made without departing from the spirit andscope thereof, and therefore only such limitations should be imposed asare indicated in the appended claims.

We claim:

\ l. The method of producing tri-isobutylene whichcomprises subjecting afeed hydrocarbon consisting essentially of di-isobutylene to the actionof sulfuric acid having a concentration of.

about 60 to 85% H2804 at a temperature in the range about to'250 F. fora relatively short period of time such that di-isobutylene undergoessubstantial conversion to tri-isobutylene with relatively smallproduction of polymer material of higher molecular weight thantri-isobutylene, separating the treated hydrocarbons from the acid andremoving tri-isobutylene from the treated hydrocarbon product.

2. The method of producing tri-'isobutylene which comprises subjecting afeed hydrocarbon consisting essentially of di-isobutylene to the actionof sulfuric acid having a concentration of about l0 to 80% HaSOi at atemperature in the y range about to 200 F. for a relatively short periodof time such that di-lsobutylene undergoes substantial conversion totri-isobutylene with relatively small production of polymeric materialof higher molecular weight than tri-isobutylene, separating the treatedhydrocarbons from the acid and removing tri-isobutylene from the treatedhydrocarbon product.

3. The method of producing tri-isobutylene which comprises subjecting anormally gaseous hydrocarbon feedv comprising isobutylene to the actionof a polymerization catalyst under conditions such that a hydrocarbonmixture is obtained which contains di-isobutylene and tri-isobutylene,separating di-isobutylene from the hydrocarbon mixture, subjecting thedi-isobutylene so obtained to the action of sulfuric acid having aconcentration of about 60 to 85% H2504 at a temperance inthe range aboutmo tu 250 E. :or

a relatively short period of time such that dibutylene,separatingdi-isobutylene from the hydrccarbon mixture, subjecting thedi-isobutylenev so obtainedl to the action of sulfuric acid havingasaaaoaf" l l 3 a concentration of about 70 to 80% H2804 at atemperature in the range about 150 to 200 F. for

a relatively short period of time such that di. isobutylene undergoessubstantial conversion tov tri-isobutylene with relatively smallproduction of polymer material of higher molecular weight thantrl-isobutylene, separating the treated hydrocarbons from the acid andremoving trl-iso- '-butylene from the treated hydrocarbon product.

5. The method according to claim 3 in which the isobutylene feed ispolymerized by the action of sulfuric acid containing about 60 to '70%H2SO4 and at a temperature in the range 40 to 200 F. v

LOUIS A. CLARKE. GEORGE B. HATCH. ERNEST E. PEVERE.

